The present invention lies in the technical field of water purification or water treatment. Water treatment is nowadays of major importance in many areas of private and commercial life. Statutory environmental regulations and health regulations also increasingly have to be adhered to. The method according to various embodiments and the apparatus according to various further embodiments can be used particularly advantageously in the area of the elimination of acid rock drainage which may occur during the industrial conveyance of raw materials in open cast mining. Acid rock drainage is waste water with a pH value markedly lower than seven, that is to say an acid solution which moreover has, as a rule, heavy metal ions dissolved in the water.
Acid rock drainage arises due to water, for example in the form of rain or snow, which trickles through a waste heap occurring during mining. If soil or conveyed material, for example on an overburden heap, comes into contact with water, for example rainwater or melt water, and air, in particular oxygen, chemical reactions take place, the consequence of which is ultimately the generation of sulfuric acid. The sulfuric acid, when it trickles through the soil or conveyed material, releases heavy metals from the soil or from the dumped conveyed material. Via natural drainages or channels, the, as a rule, heavy metal-containing acidic solution collects in a natural sink or runs, unpurified, into a river.
The water contaminated with sulfate ions and with heavy metals usually has a toxic effect on living organisms. It is therefore necessary and expedient to remove the sulfate ions and the heavy metal ions from the aqueous solution.